Which of the following is an example of a complex sentence?

a.) i want to go to sleep, but the little puppy wants to go outside.
b.) some people use social media every single day of their lives.
c.) because the monster jumped up without warning, the girl screamed.
d.) he and his friends went to the store, and she hung out at home.

C.  Because the monster jumped up without warning, the girl screamed.

check your question

comfortable

explanation:

one type of the adjectives is predicate adjective. a predicate adjective is an adjective which follows a linking verb and modifies or refers back to the main subject of that linking verb.

it usually is used just before the noun it modies.

here in this example:

'penguins seem comfortable in the coolest habitats', comfortable is the predicate adjective which follows the linking verb 'seem' and modifies the noun.